Synthesis of benzene ruthenium triazolato complexes by [3+2] cycloaddition reactions of activated alkynes and fumaronitrile to benzene ruthenium azido complexes

The dinuclear complex [(η6-C6H6)Ru(μ-N3)Cl]2 (1) is obtained by the reaction of [(η6-C6H6)RuCl2]2 with sodium azide in ethanol. The benzene ruthenium β-diketonato complexes of the general formula [(η6-C6H6)Ru(L∩L)Cl] {L∩L = O,O′-acac (2); O,O′-bzac (3); O,O′-dbzm (4)} are obtained in methanol by the reaction of [(η6-C6H6)RuCl2]2 with the corresponding β-diketonates. These complexes further react with sodium azide in ethanol to yield complexes of the type [(η6-C6H6)Ru(L∩L)N3] [L∩L = O,O′-acac (5); L∩L = O,O′-bzac (6); L∩L = O,O′-dbzm (7)]. The complexes 5–7 are obtained as well by treating 1 with sodium salts of β-diketonates. These neutral benzene ruthenium azido complexes undergo [3+2] dipolar cycloaddition reaction with activated alkynes (MeO2CCCCO2Me, EtO2CCCCO2Et) or fumaronitrile (NCHCCHCN) to yield the corresponding benzene ruthenium triazolato complexes; [(η6-C6H6)Ru(O,O′-acac){N3C2(CO2Me)2}] (8), [(η6-C6H6)Ru(O,O′-acac){N3C2(CO2Et)2}] (9), [(η6-C6H6)Ru(O,O′-acac){N3C2HCN}] (10), [(η6-C6H6)Ru(O,O′-bzac){N3C2HCN}] (11) and [(η6-C6H6)Ru(O,O′-dbzm){N3C2HCN}] (12). These complexes are fully characterized on the basis of microanalyses, FT-IR and FT-NMR spectroscopy. The molecular structure of [(η6-C6H6)Ru(O,O′- acac){N3C2(CO2C2H5)2}] (9) is confirmed by single crystal X-ray diffraction study.